DGA here means "domain generation algorithm" – malware will often find its command and control servers using dynamically-generated domain names. It makes it harder for an infected victim to sinkhole the domains, and a malware author can spin up new ones according to the algorithm as necessary.

The DNS requests causing the alerts looked innocuous to me. It turns out that Chrome purposely issues invalid DNS requests every time it starts in order to root out malicious DNS servers. Discussed here: